Heavy equipment units, such as backhoes and the like, have booms that may be detachably coupled to an implement (for example, a bucket, a rake or a grapple), which is carried by the boom to permit interchangeability of implements. Ordinary devices of this type may require several hours to complete an implement change. Attachment pins must be manually driven out of their pivotal sockets and then manually driven back into place for attachment of a different implement. Because of the size of the equipment involved, precise alignment is a challenge to achieve and adds to the difficulty of the job.
Many pieces of heavy equipment are outfitted with quick coupling devices so than an interchange of implements may be accomplished in a matter of minutes, rather than hours.
When heavy equipment, such as a backhoe, is designed, the junction between the implement, such as a bucket, and the boom (or stick), is carefully engineered. Ideally, the originally-designed axis of rotation between the implement and boom should be maintained. Some prior art quick coupling devices have failed in this regard in that this axis of rotation is undesirably shifted. In still other prior art devices, this axis of rotation is maintained, but as wear occurs at the engagement points, the point of coupling may become loose. In particular, this may be the case where lugs on the boom component of the coupling device fit between or within a spaced defined by lugs on the implement component of the coupling device.
Typically, each heavy equipment manufacturer will design a particular radial distance between the axis of rotation, at which the implement attaches to the boom, and the point of connection to the implement for rotational actuation. In the past, the components of the quick coupling devices had to be specifically designed to account for this variation. Consequently, implements built with a quick coupling component would only be interchangeable with other pieces of heavy equipment of the same class and manufacturer. Contractors or rental yards having more than one piece of heavy equipment made by different manufacturers would have to stock a separate and complete line of implements for each heavy equipment manufacturer.
U.S. Pat. No. 5,597,283 addresses this limitation. However, because the attachment lugs of the boom component fit between attachment lugs of the implement coupler component, there is a limit to the amount of wear compensation inherently available. That is, if the coupling device components are designed to be fully engaged when new, there is little or no room left for deeper or further engagement as wear occurs.
The following patents should be reviewed carefully for the purpose of putting the present invention into proper perspective: U.S. Pat. No. 3,556,323, issued Jan. 19, 1971, to Damian M. Heimmermann; U.S. Pat. No. 3,818,551, issued Jun. 25, 1974, to Samuel J. Coughran Jr.; U.S. Pat. No. 4,881,867, issued Nov. 21, 1989, to Stewart A. Essex et al.; U.S. Pat. No. 4,955,779, issued Sep. 11, 1990, to Jack S. Knackstedt; and U.S. Pat. No. 5,597,283, issued Jan. 28, 1997, to Gordon Jones.